1. The problem statement, all variables and given/known data Find the absolute max and min values of f on the set D. f(x,y)=4xy^3 - (x^2)(y^2) - xy^3 D is the closed triangular region in the xy-plane with vertices (0,0) (0,6) and (6,0). 3. The attempt at a solution I found my two critical points to be (1,2) and (2,0). Then I tried to evaluate the boundary points: 1) 0<x<6, y=0 2) 0<y<6, x=0 3) (6-y, y) because the third boundary line is y= -x+6 I don't know how to solve for the last boundary line though. I plugged in x=6-y in the original equation, got the expression (2y^3)-(12y^2). Do I just plug in numbers now? My book gets (2,4) for the absolute min, which is a point on this 3rd boundary line. I just don't see how to come up with the point, though.